Pin drive bolts splitting Help Please

David Kirkham · #1 (**permalink**) 01-09-2009, 06:52 PM

On a final note for tonight, there has been some confusion on this thread as to how angles are measured in champhers, counterbores or countersinks. In every country that I know of, the angle of a countersink in a hole is measured by the total angle the cutter makes in the hole. In other words, you take a protractor and measure the angle the cutter makes on BOTH sides of the flutes. (Pictures will help...tomorrow).

Champers, on the other hand, are defined by 1/2 of the total angle. Therefore, a 45 degree champher makes a 90 degree countersunk hole. Champers are defined by degrees because you can make a 45 degree champer on the edge of a rectangular part--the other side of which can be on the other side of the casting, or not even there at all. On a hole, however, they measure both sides.

I know it can be confusing. I added a link to a countersink supplier. Notice the industrial standards (that are used all over the world, by the way).

60, 82, 90, 100, 120 degrees...76 degrees is not used anywhere I can find.

http://www1.mscdirect.com/CGI/NNPDFF...0&PMT4TP=*LTIP

David

jmimac351 · #2 (**permalink**) 01-09-2009, 08:12 PM

Unbelievable. David, it's a credit to you that you're taking on this project to try and help these guys. Nice going.

Dominik · #3 (**permalink**) 01-09-2009, 10:03 PM

Nice going! :-)

Please can someone fit the pins on a stud or bolt and turn them in a lathe or drill press.
I would like to know if they are concentric. Or how much they "run out".

You could also fit them (2) on a hub. Measure the gap with a vernier caliper between the two. Then turn them half a turn and measure again. Do that until you get the biggest difference.

Dom

David Kirkham · #4 (**permalink**) 01-09-2009, 10:34 PM

Dom,

No, they are not concentric. You can tell just by screwing them on. I will post TIR tomorrow. I was too busy to measure accurately, but when I saw them wobbling, I gave up and moved on to other things.

I will post some very, very interesting photos tomorrow.

David

Paul F · #5 (**permalink**) 01-10-2009, 09:24 AM

Here are some pictures of the Compomotive hub and pin. I suspect Trigo uses the same pin, manufactured by someone else. David, let us know if they look like the same piece.

From the pictures, it's clear there are two different angles. The 76 degrees that David measured on the pin and then perhaps 90 degrees on the hub.

Here is the hub, pin drive and hex wrench

Here is the pin showing the contact area with the hub. Notice its only contacting on the inner edge.

Here is the hub showing the same contact on the inner edge.

Clearly two different angles.